Non-aqueous dispersions have previously been found to be useful as rheology control and toughening agents in coating applications. Known non-aqueous dispersions typically comprise a core of material that is not soluble in the solvent system, and, attached to the core, a stabilizing component which is soluble in the solvent system used. In the reactive system, the stabilizer may act as a compatibilizer. The quantity of stabilizer attached to the core is adjusted to solubize the entire structure in the coating composition.
In the past, non-aqueous dispersions have been prepared using stabilizers having polymerizable functional groups randomly distributed along the chain of the stabilizer. With the random distribution of the polymerizable functional groups along the chain, the effectiveness of the non-aqueous dispersion was less than optimal, and effort has been directed toward the development of non-aqueous dispersions that would provide equivalent or superior performance with a more compact molecule.
The use of chain transfer agents for the preparation of stabilizing components used in non-aqueous dispersions can result in functional groups at the end of the stabilizer molecule, but typically in only 40 to 70 percent of the resulting products. Consequently, substantial quantities of non-polymerizeable linear polymers are present in the final, stabilized resin prepared from such stabilizers. The presence of such polymers has an undesirable plasticizing effect, and would depreciate the resistance of coatings prepared from such resins to solvents such as gasoline.
Still other previous attempts at preparing stabilized acrylic resin have included the preparation of multi-functional or multi-segmented stabilizers, each of which is less than completely satisfactory from the standpoint of product performance or uniformity.